Method for producing a supported metal nitrate

Abstract

A method for the preparation of a supported metal nitrate, suitable as a precursor for a catalyst or sorbent, includes the steps of: (i) impregnating a support material with a metal nitrate, (ii) optionally drying the impregnated material at low temperature, and (iii) exposing the impregnated material to a gas mixture comprising nitric oxide at a temperature in the range 0-150° C., to form a dispersed supported metal nitrate. The metal nitrate may subsequently be converted to the corresponding oxide by calcining the metal nitrate to effect its decomposition. Preferred metals are iron, ruthenium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper or a mixture thereof.

1 . A method for the preparation of a supported metal oxide, suitable as a precursor for a catalyst or sorbent, comprising the steps of:
 (i) impregnating a support material with a metal nitrate,   (ii) exposing the impregnated material to a gas mixture comprising nitric oxide at a temperature in the range 0-150° C., to form a dispersed supported metal nitrate, and   (iii) calcining the metal nitrate to effect its decomposition and form a supported metal oxide, wherein the calcination is performed under a gas mixture that contains nitric oxide, nitrous oxide or a mixture thereof and has an oxygen content of ≦5% by volume.   
     
     
         2 . A method according to  claim 1 , wherein the metal nitrate comprises a transition metal nitrate. 
     
     
         3 . A method according to  claim 2  wherein the dispersed supported metal nitrate comprises a metal nitrate of formula M x (OH) y (NO 3 ) z  in which x, y and z are integers ≧1 and M is a transition metal. 
     
     
         4 . A method according to  claim 1 , wherein the support is a metal, carbon, metal oxide, mixed metal oxide or solid polymer support. 
     
     
         5 . A method according to  claim 1 , wherein the support is selected from the group consisting of alumina, metal-aluminate, silica, aluminosilicate, zinc oxide, titania, zirconia and mixtures of these. 
     
     
         6 . A method according to  claim 1 , wherein the gas mixture for exposing the impregnated material has an oxygen (O 2 ) content ≦5% by volume. 
     
     
         7 . A method according to  claim 1 , wherein the gas mixture for exposing the impregnated material consists of one or more inert gases and nitric oxide. 
     
     
         8 . A method according to  claim 7 , wherein the inert gas is selected from the group consisting of nitrogen, helium and argon. 
     
     
         9 . A method according to  claim 1 , wherein the nitric oxide concentration in the gas mixture for exposing the impregnated material is in the range 0.001 to 15% by volume. 
     
     
         10 . A method according to  claim 1 , wherein the impregnated material is exposed to the nitric oxide-containing gas mixture at a temperature in the range 10-120° C. 
     
     
         11 . A method according to  claim 1 , further comprising a step of drying the impregnated material under vacuum, air or an inert gas at a temperature below 60° C., before exposing the metal nitrate to the nitric oxide-containing gas mixture. 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . A method according to  claim 1 , wherein the supported metal oxide is a reducible metal oxide, further comprising a step of heating the supported metal oxide under a reducing gas stream containing a reductant selected from the group consisting of carbon monoxide, hydrogen, and mixtures thereof to effect reduction of at least a part of the metal oxide. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . A supported oxide obtainable by the method of  claim 1 . 
     
     
         18 . A supported reduced metal oxide obtainable by the method of  claim 14 . 
     
     
         19 . A method according to  claim 2  wherein the dispersed supported metal nitrate comprises a metal nitrate of formula M x (OH) y (NO 3 ) z  in which x, y and z are integers ≧1 and M is iron, ruthenium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper or a mixture thereof. 
     
     
         20 . A method according to  claim 2  wherein the dispersed supported metal nitrate comprises a metal nitrate of formula M x (OH) y (NO 3 ) z  in which x, y and z are integers ≧1 and M is copper, nickel or cobalt. 
     
     
         21 . A method according to  claim 2  wherein the dispersed supported metal nitrate comprises a metal nitrate of formula M x (OH) y (NO 3 ) z  in which x, y and z are integers ≧1 and M is copper. 
     
     
         22 . A method according to  claim 1 , wherein the impregnated material is exposed to the nitric oxide-containing gas mixture at a temperature in the range 25-75° C.